A. Technical Field
The present invention relates to: an acrylic acid-maleic acid copolymer (or its salt) which is excellent in performances such as metal ion scavengeability, clay dispersibility, and scale inhibitability, and has a high random degree; a production process therefor; and uses of this copolymer (or its salt) for such as detergent builders.
The present invention further relates to a production process for an aqueous maleic salt solution with a low impurity content which has the advantage of giving the above copolymer (or its salt) more excellent performance.
B. Background Art
Generally, copolymers (or their salts), as used for detergent builders, water-treating agents, various chelating agents, and so on, are required to be high both in the metal ion scavengeability and the clay dispersibility in the presence of metal ions. Thus, various maleic acid copolymers (or their salts) have been developed to satisfy these performances. Furthermore, in water-treating processes, the alkaline earth metal ion scale inhibitability is demanded as an important performance, and the use of conventionally known maleic acid copolymers (or their salts) have been recognized to improve the scale inhibitability upon calcium ion that is the main component of the scale. However, in the case where such polymers (or their salts) as improved in the metal ion scavengeability, the clay dispersibility, and the scale inhibitability upon calcium are used for detergent builders, excellent deterging effects are exhibited according to expectation in some regions, while the hygroscopicity and touch of washed clothes are bad in other regions. In addition, there are problems in that the performances, such as the detergency or the softness of fibers after washing, vary with regions where the above polymers (or their salts) are used.
The present inventors diligently studied to pursue causes of the above problems. As a result, the present inventors have found that the cause is the formation of scale due to the generation of an inactive salt (magnesium hydroxide) from magnesium ion. That is to say, they have found that the generation and deposition of magnesium hydroxide scale have a bad influence upon the hygroscopicity and touch of clothes especially in regions where the magnesium ion content in water is high. Thus, the present inventors have further found out a copolymer (or its salt) which does not only maintain conventional performance levels of the metal ion scavengeability, the clay dispersibility, and the scale inhibitability upon calcium ion, but is also at high level in the scale inhibitability upon magnesium ion as has never been studied.
By the way, the production of the maleic acid copolymer (or its salt) involves the production of an aqueous maleic salt solution which is an aqueous solution of a monomer of the maleic acid copolymer (or its salt), but the production process for the aqueous maleic salt solution has never been studied.
The present inventors considered the production process for the aqueous maleic salt solution to be particularly important, and thus studied it. As a result, the present inventors found that a specific production process can give an aqueous maleic salt solution which contains only a small amount of formed impurities such as malic acid and therefore has high purity, and further that the resultant maleic acid copolymer (or its salt) from such an aqueous maleic salt solution also contains only a small amount of impurities such as malic acid and is therefore a copolymer (or its salt) which exhibits high calcium ion scavengeability and high clay dispersibility.
A. Objects of the Invention
Thus, a first object of the present invention is to provide: an acrylic acid-maleic acid copolymer (or its salt) which is excellent with good balance in performances such as metal ion scavengeability, clay dispersibility, calcium carbonate scale inhibitability, and magnesium hydroxide scale inhibitability; a production process therefor; and uses of this copolymer (or its salt) for such as detergent builders.
A second object of the present invention is to provide a production process for an aqueous maleic salt solution which contains only a small amount of formed impurities such as malic acid and therefore has high purity.
B. Disclosure of the Invention
An acrylic acid-maleic acid copolymer (or its salt), according to the present invention, is characterized by having a magnesium ion scavengeability of 210 mg (in terms of Mg(OH)2)/g or more and a magnesium hydroxide scale inhibitability of 30% or more. Preferably, this copolymer (or its salt) further has a clay dispersibility of 60% or more in the presence of magnesium ion.
Another acrylic acid-maleic acid copolymer (or its salt), according to the present invention, has a magnesium ion scavengeability of 210 mg (in terms of Mg(OH)2)/g or more, a molecular weight distribution of 3.5 or less, and low-molecular fractions with a molecular weight of 1,000 or less in the ratio of 9 wt % or less to the total of the copolymer (or its salt).
A production process for an acrylic acid-maleic acid copolymer (or its salt), according to the present invention, comprises the step of copolymerizing ethylenically unsaturated monomers including acrylic acid and maleic acid in the presence of a polymerization initiator, and is characterized in that: 50 wt % or more of the maleic acid is initially charged; the maleic acid has a neutralization degree of 70xcx9c95 mol % before the polymerization initiator is charged; and the resultant acrylic acid-maleic acid copolymer (or its salt) has a neutralization degree of 50xcx9c70 mol % and a solid component concentration of 45 wt % or more at the end of the polymerization.
A detergent composition, according to the present invention, comprises the above present invention acrylic acid-maleic acid copolymer (or its salt) and a surfactant.
A detergent builder, according to the present invention, comprises the above present invention acrylic acid-maleic acid copolymer (or its salt).
A production process for an aqueous maleic salt solution, according to the present invention, is characterized by comprising the steps of: charging 80% or less of the required amount of a basic substance to produce the aqueous maleic salt solution and 80% or less of the required amount of maleic acid (or its salt) and/or maleic anhydride to produce the aqueous maleic salt solution into a reaction vessel; and then adding thereto the respective balances of water, the basic substance, and the maleic acid (or its salt) and/or maleic anhydride under conditions where the highest value of the reaction temperature will be 80xc2x0 C. or higher; and this process can give an aqueous maleic salt solution with a formed malic acid content of not more than 10,000 ppm.
The present invention can provide a maleic acid/acrylic acid copolymer (or its salt), which comprises maleic acid (or its salt) of 30xcx9c70 mol % and acrylic acid (or its salt) of 70xcx9c30 mol %, and has a weight-average molecular weight of 2,000xcx9c50,000, a calcium ion scavengeability of 400 mg CaCO3/g or more, a clay dispersibility of 0.6 or more, and a malic acid content of not more than 9 wt % in the solid content of the copolymer (or its salt).
These and other objects and the advantages of the present invention will be more fully apparent from the following detailed disclosure.
In this part I, detailed descriptions are given on the present invention acrylic acid-maleic acid copolymer (or its salt) and its production process and use.
(Acrylic acid-maleic acid copolymer (or its salt):
The magnesium ion scavengeability of the present invention acrylic acid-maleic acid copolymer (or its salt) is defined as the mg number, in terms of magnesium hydroxide (Mg(OH)2), of magnesium ion as scavenged by 1 g of the copolymer (or its salt), and, for example, can be measured by the method as described in the below-mentioned examples of some preferred embodiments. The magnesium ion scavengeability is an index to show how much magnesium ion in water the acrylic acid-maleic acid copolymer (or its salt) scavenges. The surfactant, as used for detergents, becomes insoluble upon bonding to magnesium ion in water, so that the detergency deteriorates. However, if, even when the fiber is treated with magnesium-ion-containing water, the present invention acrylic acid-maleic acid copolymer (or its salt) having high magnesium ion scavengeability is used together with the surfactant, then the surfactant is prevented from becoming insoluble, so that the detergency upon dirt such as oil dirt can be prevented from deteriorating, and further, the magnesium scale can be prevented from deposition to fibers. Such effects can lessen the variation of the performance of detergent materials, such as detergent compositions and detergent builders, with regions.
The magnesium ion scavengeability of the present invention acrylic acid-maleic acid copolymer (or its salt) is usually 210 mg/g or more (in terms of Mg(OH)2 as scavenged by 1 g of the acrylic acid-maleic acid copolymer (or its salt)), preferably 220 mg (in terms of Mg(OH)2)/g or more, more preferably 230 mg (in terms of Mg(OH)2)/g or more, still more preferably 240 mg (in terms of Mg(OH)2)/g or more. The increase in the magnesium ion scavengeability enhances the ability of the acrylic acid-maleic acid copolymer (or its salt) as the detergent builder in the presence of magnesium ion.
The clay dispersibility of the present invention acrylic acid-maleic acid copolymer (or its salt) in the presence of magnesium ion is defined as the value (%) of the absorbance as measured by the method as described in the below-mentioned examples of some preferred embodiments.
The clay dispersibility in the presence of magnesium ion is an index for evaluation of effects upon removing and uniformly dispersing the dirt such as mud dirt, thereby preventing the clay from precipitating, in the case where water, as used for washing, contains magnesium ion. To sufficiently obtain such effects, the above clay dispersibility is preferably 60% or more, and further, to prevent the deposition of mud dirt, the clay dispersibility is more preferably 70% or more, still more preferably 73% or more, most preferably 75% or more.
The clay dispersibility in the presence of magnesium ion is a numerical value to evaluate the dispersion extent of the clay in the presence of magnesium ion and the copolymer (or its salt) on the basis of the turbidity of a supernatant as produced by allowing a suspension of dispersed clay to stand stationary for a certain time. The larger numerical value shows higher clay dispersibility.
The magnesium hydroxide scale inhibitability and the calcium carbonate scale inhibitability of the present invention acrylic acid-maleic acid copolymer (or its salt) are defined as the magnesium hydroxide inhibition rate (%) and the calcium carbonate inhibition rate (%) respectively as measured by the methods as described in the below-mentioned examples of some preferred embodiments, and are indices to show how much the acrylic acid-maleic acid copolymer (or its salt) prevents the generation and deposition of the magnesium hydroxide scale and calcium carbonate scale in water systems. The larger numerical values of the above scale inhibition rates (%) show that their respective scale inhibitabilities are higher. In the case where the magnesium hydroxide scale or calcium carbonate scale is generated and deposited in water systems, bad influences are produced, for example, as follows: piping is clogged, or the detergency of detergents is lowered, or clothes are blacked (especially, the deposition of magnesium hydroxide scale to clothes will overstarch the clothes to deteriorate their hygroscopicity and touch). However, if the present invention acrylic acid-maleic acid copolymer (or its salt) having high magnesium hydroxide scale inhibitability and high calcium carbonate scale inhibitability is used, then the generation and deposition of the magnesium hydroxide scale and calcium carbonate scale can be prevented to avoid the above bad influences.
The magnesium hydroxide scale inhibitability of the present invention acrylic acid-maleic acid copolymer (or its salt) is usually 30% or more, preferably 33% or more, more preferably 35% or more, still more preferably 37% or more, to sufficiently obtain the above effects.
The calcium carbonate scale inhibitability of the present invention acrylic acid-maleic acid copolymer (or its salt) is usually 60% or more, preferably 70% or more, more preferably 75% or more, still more preferably 78% or more, yet still more preferably 80% or more, to sufficiently obtain the above effects.
The weight-average molecular weight of the present invention acrylic acid-maleic acid copolymer (or its salt) is preferably in the range of 2,000xcx9c100,000, more preferably 3,000xcx9c50,000, still more preferably 5,000xcx9c20,000, most preferably 6,000xcx9c15,000. In the case where the weight-average molecular weight is less than 2,000, the magnesium ion scavengeability tends to be so low as to deteriorate the detergency. In the case where the weight-average molecular weight exceeds 100,000, the clay dispersibility in the presence of magnesium ion or the magnesium hydroxide scale inhibitability tends to be low.
Furthermore, for more enhancing the magnesium ion scavengeability, it is very preferable that the molecular weight distribution, namely, Mw/Mn as given by dividing the weight-average molecular weight (Mw) by the number-average molecular weight (Mn), of the present invention acrylic acid-maleic acid copolymer (or its salt) is 3.5 or less, more preferably 3.0 or less, and further that the present invention acrylic acid-maleic acid copolymer (or its salt) has low-molecular fractions with a molecular weight of 1,000 or less in the ratio of 9 wt % or less, more preferably 6 wt % or less, to the total of the copolymer (or its salt).
The production process for the present invention acrylic acid-maleic acid copolymer (or its salt) is not especially limited. However, for example, the below-mentioned production process according to the present invention is preferable.
(Production process for acrylic acid-maleic acid copolymer (or its salt)):
The production process according to the present invention is a process comprising the step of copolymerizing ethylenically unsaturated monomers including acrylic acid and maleic acid in the presence of a polymerization initiator, thereby obtaining the acrylic acid-maleic acid copolymer (or its salt).
In this process, the amount of maleic acid, as initially charged, is usually 50 wt % or more, preferably 80 wt % or more, most preferably 100 wt % (initially charging the entirety), of the entirety of maleic acid as used. In the case where the amount of maleic acid, as initially charged, is smaller than 50 wt %, the amount of unreacted maleic acid is so large in the latter half of the polymerization that maleic acid cannot uniformly be introduced into the resultant copolymer (or its salt), therefore the resultant magnesium ion scavengeability is low, and the resultant magnesium hydroxide scale inhibitability is also low.
The neutralization degree of maleic acid is usually in the range of 70xcx9c95 mol %, preferably 75xcx9c90 mol %, more preferably 80xcx9c87 mol %, before the polymerization initiator is charged. In the case where this neutralization degree is less than 70 mol %, maleic acid is polymerized in the block form, so the resultant clay dispersibility in the presence of magnesium ion is low. In the case where the above neutralization degree exceeds 95 mol %, the introducing efficiency of maleic acid is so bad that the resultant magnesium ion scavengeability is so low as to deteriorate not only the detergency, but also the magnesium hydroxide scale inhibitability.
The initial solid component concentration of maleic acid is preferably 48 wt % or more, more preferably 50 wt % or more, still more preferably 53 wt % or more, of the entirety of the initial reaction liquid. In the case where the initial solid component concentration of maleic acid is less than 48 wt %, the introducing efficiency of maleic acid tends to be so bad that the resultant magnesium ion scavengeability is so low as to deteriorate not only the detergency, but also the magnesium hydroxide scale inhibitability.
The form of maleic acid, as used, may be any of maleic anhydride, maleic acid, and maleic salt, and any mixture thereof is also available. In addition, when used, maleic anhydride or maleic acid is fitly partially neutralized to a predetermined neutralization degree with an alkaline substance, if necessary. The above alkaline substance is not especially limited, but examples thereof include: alkaline metal hydroxides, such as sodium hydroxide and potassium hydroxide; ammonia; and organic amines, such as monoethanolamine. These may be used either alone respectively or in combinations with each other.
Acrylic acid is added to the reaction system by dropping preferably 70 wt % or more, more preferably 90 wt % or more, most preferably 100 wt %, of the entirety thereof as used. In the case where the ratio of acrylic acid, as dropped, is less than 70 wt %, initial acrylic acid is polymerized in the block form, so the resultant magnesium hydroxide scale inhibitability tends to be low.
The dropping duration of acrylic acid is preferably in the range of 30xcx9c240 minutes, more preferably 90xcx9c150 minutes, still more preferably 100xcx9c140 minutes. In the case where the dropping duration of acrylic acid is shorter than 30 minutes, acrylic acid is polymerized in the block form, so the resultant magnesium hydroxide scale inhibitability tends to be low. In the case where the dropping duration of acrylic acid exceeds 240 minutes, maleic acid is polymerized in the block form, so the resultant clay dispersibility in the presence of magnesium ion tends to be low.
The form of acrylic acid, as used, is, especially preferably, acrylic acid. An acrylic salt may be used by adding it to acrylic acid, if necessary. But the ratio of the acrylic salt, as added, is set to such that the neutralization degree of the acrylic acid-maleic acid copolymer (or its salt) will be in the below-mentioned range. The above acrylic salt is not especially limited, but examples thereof include: alkaline metal acrylates, such as sodium acrylate and potassium acrylate; ammonium acrylate; and organic amine salts of acrylic acid. These may be used either alone respectively or in combinations with each other.
The ratio between acrylic acid and maleic acid as used for copolymerization (acrylic acid/maleic acid (molar ratio)) is preferably in the range of 30/70xcx9c70/30, more preferably 35/65xcx9c65/35, still more preferably 40/60xcx9c60/40. In the case where the ratio of acrylic acid, as used, is less than 30/70, the resultant magnesium ion scavengeability tends to be so low as to deteriorate the magnesium hydroxide scale inhibitability. In the case where the ratio of acrylic acid, as used, exceeds 70/30, the resultant magnesium ion scavengeability tends to be low, and the resultant clay dispersibility in the presence of magnesium ion also tends to be low.
Acrylic acid and maleic acid are essentially used as the ethylenically unsaturated monomers. However, if necessary, another ethylenically unsaturated monomer may be used jointly with acrylic acid and maleic acid within the range where the effect of the present invention is not damaged.
The above other ethylenically unsaturated monomer, which can be used jointly, is not especially limited if it is copolymerizable with acrylic acid and maleic acid. But examples thereof include: unsaturated monocarboxylic acid monomers, such as methacrylic acid and crotonic acid; unsaturated dicarboxylic acid monomers and unsaturated polycarboxylic acid monomers, such as fumaric acid, itaconic acid, citraconic acid, and aconitic acid; amide monomers, such as (meth)acrylamide and t-butyl(meth)acrylamide; hydrophobic monomers, such as (meth)acrylic esters, styrene, 2-methylstyrene, and vinyl acetate; unsaturated sulfonic acid monomers, such as vinylsulfonic acid, allylsulfonic acid, methallylsulfonic acid, styrenesulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, 3-allyloxy-2-hydroxypropanesulfonic acid, sulfoethyl (meth)acrylate, sulfopropyl (meth)acrylate, 2-hydroxysulfopropyl (meth)acrylate, and sulfoethylmaleimide; neutralized products as formed by partially or entirely neutralizing the above unsaturated monocarboxylic acid monomers, the above unsaturated dicarboxylic acid monomers, the above unsaturated polycarboxylic acid monomers, or the above unsaturated sulfonic acid monomers with, for example, monovalent metals, divalent metals, ammonia, or organic amines; hydroxyl-group-containing unsaturated monomers, such as 3-methyl-2-buten-1-ol (which might be referred to as xe2x80x9cprenolxe2x80x9d), 3-methyl-3-buten-1-ol (which might be referred to as xe2x80x9cisoprenolxe2x80x9d), 2-methyl-3-buten-2-ol (which might be referred to as xe2x80x9cisoprene alcoholxe2x80x9d), 2-hydroxyethyl (meth)acrylate, polyethylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, polyethylene glycol monoisoprenol ether, polypropylene glycol monoisoprenol ether, polyethylene glycol monoallyl ether, polypropylene glycol monoallyl ether, glycerol monoallyl ether, xcex1-hydroxyacrylic acid, N-methylol(meth)acrylamide, glycerol mono(meth)acrylate, vinyl alcohol, and xcex1-hydroxyalkyl acrylates; cationic monomers, such as dimethylaminoethyl (meth)acrylate and dimethylaminopropyl(meth)acrylamide; nitrile monomers, such as (meth)acrylonitrile; phosphorus-containing monomers, such as (meth)acrylamidomethane phosphonic acid, methyl (meth)acrylamidomethanephosphonate, and 2-(meth)acrylamido-2-methylpropanephosphonic acid; alkyl vinyl ethers, such as methyl vinyl ether and ethyl vinyl ether; and vinylpyrrolidone. These monomers may be used either alone respectively or in combinations with each other.
The polymerization initiator is not especially limited, but examples thereof include: hydrogen peroxide; persulfuric acid salts, such as ammonium persulfate, sodium persulfate and potassium persulfate; azo compounds, such as 2,2xe2x80x2-azobis(2-amidinopropane) dihydrochloride, 4,4xe2x80x2-azobis-(4-cyanovaleric acid), 2,2xe2x80x2-azobisisobutyronitrile and 2,2xe2x80x2-azobis(4- methoxy-2,4-dimethylvaleronitrile); organic peroxides, such as benzoyl peroxide, lauroyl peroxide, peracetic acid, persuccinic acid, di-tertiary-butyl peroxide, di-tertiary-butyl hydroperoxide and cumene hydroperoxide. These may be used either alone respectively or in combinations with each other. Among them, the use of hydrogen peroxide or persulfuric acid salt is preferable, and the joint use of hydrogen peroxide and persulfuric acid salt is more preferable.
In the case where hydrogen peroxide is used as the polymerization initiator, it is preferable to finish charging hydrogen peroxide earlier than the charging end of all the monomers, more preferably, by 10 minutes or more, considering the simplification of production facilities, the cost saving, and effects of lessening the amount of hydrogen peroxide remaining at the end of the polymerization. In other words, it is preferable to finish charging hydrogen peroxide in a state where polymerizable raw monomers still remain in the reaction system.
The amount of the polymerization initiator, as used, is not especially limited, but is, for example, preferably in the range of 1xcx9c20 wt %, more preferably 3xcx9c15 wt %, still more preferably 5xcx9c12 wt %, of the total weight of the monomers as used. In the case where the amount of the polymerization initiator, as used, is smaller than 1 wt %, maleic acid tends not to efficiently be introduced into the resultant copolymer (or its salt). In the case where the amount exceeds 20 wt %, the resultant magnesium ion scavengeability tends to be low because of low molecular weight of the resultant copolymer (or its salt).
As to the polymerization solvent, aqueous solvents are used. Particularly preferably, water is used alone. However, a hydrophilic organic solvent may be used by fitly adding it to water, if necessary.
The above hydrophilic organic solvent is not especially limited, but examples thereof include: lower alcohols, such as methanol and ethanol; amides, such as dimethylformamide; and ethers, such as diethyl ether. These may be used either alone respectively or in combinations with each other.
The ratio of the hydrophilic organic solvent, as used, is preferably 20 wt % or less, more preferably 10 wt % or less, still more preferably 1 wt % or less, of the total amount of a mixed solvent with water. In the case where this ratio exceeds 20 wt %, maleic acid has a tendency not to efficiently be introduced into the resultant copolymer (or its salt).
The polymerization temperature is not especially limited, but is preferably 80xc2x0 C. or higher, more preferably 100xc2x0 C. or higher or a temperature near the boiling point of the polymerization solvent, for example, in view of efficient introduction of maleic acid into the resultant copolymer (or its salt).
The polymerization pressure is not especially limited, but any of normal pressure (atmospheric pressure), an increased pressure, and a reduced pressure is available.
The neutralization degree of the resultant acrylic acid-maleic acid copolymer (or its salt) is set to be usually in the range of 50xcx9c70 mol %, preferably 52xcx9c68 mol %, more preferably 55xcx9c65 mol %, at the end of the polymerization. In the case where this neutralization degree is less than 50 mol %, maleic acid is introduced into the resultant copolymer (or its salt) in the block form, resulting in the deterioration of the clay dispersibility in the presence of magnesium ion. In the case where the above neutralization degree exceeds 70 mol %, the ratio of maleic acid as introduced is so low that the resultant magnesium ion scavengeability is low, and that the amount of residual maleic acid is large.
The neutralization degree of the resultant acrylic acid-maleic acid copolymer (or its salt) is in the above specific range at the end of the polymerization, but, after the end of the polymerization, the neutralization degree may be changed to any value by conventional methods, if necessary.
The solid component concentration of the resultant acrylic acid-maleic acid copolymer (or its salt) is set to be preferably 45 wt % or higher, more preferably 48 wt % or higher, still more preferably 49 wt % or higher, yet still more preferably 50 wt % or higher, of the entirety of the reaction liquid at the end of the polymerization. In the case where this solid component concentration is lower than 45 wt %, the resultant magnesium ion scavengeability tends to be low because of low molecular weight of the resultant copolymer (or its salt).
The acrylic acid-maleic acid copolymer (or its salt), according to the present invention, can favorably be used, for example, for detergent compositions, detergent builders, water-treating agents (e.g. scale inhibitors for industries, scale inhibitors for oil fields, and scale inhibitors for pulp digesters), pigment dispersants, fiber-treating agents (e.g. bleaching assistants, fiber-scouring assistants, and dyeing assistants), and soil dispersants (e.g. adjusting agents for bentonite muddy water, ground-improving dispersants for high pressure jet processing methods). Hereinafter, explanations are specifically made on detergent compositions, detergent builders, water-treating agents, pigment dispersants, and fiber-treating agents as particularly preferable uses, as selected from among the above various uses, of the present invention acrylic acid-maleic acid copolymer (or its salt).
(Detergent composition):
The detergent composition, according to the present invention, comprises the present invention acrylic acid-maleic acid copolymer (or its salt) and a surfactant.
In the detergent composition of the present invention, the ratio of the present invention acrylic acid-maleic acid copolymer (or its salt) and the surfactant as mixed is not especially limited. However, for example, in view of scavenging the magnesium ion from tap water, dispersing the clay, and preventing the deposition of magnesium hydroxide scale, the ratio to the entirety of the detergent composition is preferably such that: the present invention acrylic acid-maleic acid copolymer (or its salt) is in the range of 1xcx9c20 wt %, and the surfactant is in the range of 5xcx9c60 wt %, and more preferably, the present invention acrylic acid-maleic acid copolymer (or its salt) is in the range of 2xcx9c18 wt %, and the surfactant is in the range of 10xcx9c55 wt %.
In addition, the present invention detergent composition may comprise the present invention acrylic acid-maleic acid copolymer (or its salt) and the surfactant, or may further comprise acrylic acid-maleic acid copolymers (or their salts) other than the present invention acrylic acid-maleic acid copolymer (or its salt), or yet other polymers or copolymers (or their salts), for specific example, conventional polymer builders such as glyoxylic acid polymers (or their salts) and polyaspartic acid polymers (or their salts), if they do not hinder the performance or effects of the present invention detergent composition.
As to the surfactant, at least one member selected from the group consisting of anionic surfactants, nonionic surfactants, amphoteric surfactants and cationic surfactants can preferably be used.
The anionic surfactant is not especially limited, but examples thereof include alkylbenzenesulfonic acid salts, alkyl or alkenyl ether sulfuric acid salts, alkyl or alkenyl sulfuric acid salts, xcex1-olefinsulfonic acid salts, xcex1-sulfofatty acids or any ester salt thereof, alkanesulfonic acid salts, saturated or unsaturated fatty acid salts, alkyl or alkenyl ether carboxylic acid salts, amino acid surfactants, N-acylamino acid surfactants, and alkyl or alkenyl phosphoric acid esters or any salt thereof. One or more kinds can be fitly selected from among these surfactants and used.
The nonionic surfactant is not especially limited, but examples thereof include polyoxyalkylene alkyl ethers, polyoxyalkylene alkenyl ethers, polyoxyethylene alkyl phenyl ethers, higher fatty acid alkanolamide or any alkylene oxide addition product thereof, sucrose fatty acid esters, alkyl glycoxides, fatty acid glycerol monoesters, and alkylamine oxides. One or more kinds can be fitly selected from among these surfactants and used.
The amphoteric surfactant is not especially limited, but, for example, one or more of carboxy or sulfobetaine amphoteric surfactants are usable.
The cationic surfactant is not especially limited, but, for example, one or more of quaternary ammonium salts are usable.
The detergent composition of the present invention may further comprise an enzyme in order to enhance the detergency, if necessary.
The enzyme, as can be mixed, is not especially limited, but examples of usable enzymes include protease, lipase, and cellulase. Particularly preferred are protease, alkaline lipase, and alkaline cellulase, all of which are highly active in alkaline washing liquids. The amount of the enzyme, as mixed, is preferably within the range of 0.01 to 1 wt % of the entirety of the detergent composition. In the case where the amount deviates from this range, the balance with the surfactant is lost, so the enhancement of the detergency tends to be impossible.
The detergent composition of the present invention, if necessary, may further comprise components which are usually used for conventional detergent compositions, such as alkaline builders, chelate builders, re-attachment inhibitors, fluorescent agents, bleachers and perfumes. In addition, zeolite may also be added. The addition of zeolite is preferable for greatly enhancing the detergency. Examples of usable alkaline builders include silicic acid salts, carbonic acid salts, and sulfuric acid salts. Examples of the chelate builder, as can be used if necessary, include HIDS (hydroxyiminodisuccinic acid salts), IDS (iminodisuccinic acid salts), CMOS (carboxymethyloxysuccinates), diglycolic acid, oxycarboxylic acid salts, EDTA (ethylenediaminetetraacetic acid), DTPA (diethylenetriaminehexaacetic acid), citric acid, and ss-EDDS (ss-ethylenediaminesuccinates). In addition, substances, such as products by addition reaction of EO (ethylene oxide) to polyethylenimine, may further be used as soil releasing agents in order to enhance the detergency.
The detergent composition of the present invention is favorably used as a detergent for clothes. Particularly, this composition, having high scavengeability upon metal ions including magnesium ion, is very effective for inhibiting the yellowing due to a slight amount of metals, which are present in washing liquids, such as iron ions and zinc ions.
Because the detergent composition of the present invention contains the present invention acrylic acid-maleic acid copolymer (or its salt) which has excellent clay dispersibility in the presence of magnesium ion and excellent magnesium ion scavengeability, this detergent composition is well balanced between (1) an effect to disperse mud dirt and (2) an effect to remove oil dirt by inhibiting the insolubilization of the surfactant in the detergent composition by scavenging metal ions, including magnesium ion, even if the magnesium ion is present in water as used for washing. Thus, the detergent composition of the present invention is a high performance detergent composition.
(Detergent builder):
The detergent builder, according to the present invention, comprises the present invention acrylic acid-maleic acid copolymer (or its salt).
The detergent builder of the present invention may comprise the present invention acrylic acid-maleic acid copolymer (or its salt), or may comprise the joint use of this acrylic acid-maleic acid copolymer (or its salt) with conventional detergent builders, such as alkaline builders, chelate builders, glyoxylic acid polymers (or their salts), and polyaspartic acid polymers (or their salts), or with other polymers (or their salts). The amount of these materials, jointly usable with the present invention acrylic acid-maleic acid copolymer (or its salt), is not especially limited if those materials do not hinder the performance or effects of the present invention detergent builder. The content of the present invention acrylic acid-maleic acid copolymer (or its salt) in the present invention detergent builder is preferably in the range of 1xcx9c100 wt %, more preferably 5xcx9c100 wt %, of the entirety of the detergent builder. Specific examples of the alkaline builder and the chelate builder include the same as exemplified above as those which can be added to the detergent composition of the present invention.
(Water-treating agent):
The water-treating agent, comprising the present invention acrylic acid-maleic acid copolymer (or its salt), is excellent in dispersibility and other performances, such as chelating ability and scale inhibitability, even in regions where the magnesium ion content in water is high. Therefore, this water-treating agent is useful for inhibiting the formation of magnesium hydroxide scale and calcium carbonate scale in systems such as cooling water circulation systems, boiler water circulation systems, seawater desalination plants, pulp digesters, and black liquor evaporators. Not only may the acrylic acid-maleic acid copolymer (or its salt) be used alone as the water-treating agent, but it may be used as the water-treating agent in the form of a composition which further comprises additives such as polymeric phosphoric acid salts, phosphonic acid salts, anticorrosive agents, slime controlling agents, and chelating agents. In addition, the water-treating agent may further comprise polymers (or their salts) other than the present invention acrylic acid-maleic acid copolymer (or its salt) if they do not hinder the performance or effects of the water-treating agent.
In the water-treating agent comprising the present invention acrylic acid-maleic acid copolymer (or its salt), the content of this copolymer (or its salt) is preferably in the range of 5xcx9c100 wt %, more preferably 10xcx9c99 wt %, most preferably 20xcx9c80 wt %, of the solid content of the water-treating agent.
The amount of the water-treating agent, which comprises the present invention acrylic acid-maleic acid copolymer (or its salt) and is added to the water system, is not especially limited, but is preferably in the range of 0.1xcx9c100 ppm, more preferably 0.5xcx9c50 ppm, most preferably 1xcx9c20 ppm, in the water system.
(Pigment dispersant):
The pigment dispersant, comprising the present invention acrylic acid-maleic acid copolymer (or its salt), is excellent in pigment dispersibility even in regions where the magnesium ion content in water is high. Therefore, this pigment dispersant exhibits good performance as a dispersant for pigments, for example, inorganic pigments, such as heavy or light calcium carbonate (as used for paper coating), clay, titanium oxide, magnesium hydroxide, iron oxide, and alumina, and organic pigments, such as carbon black and phthalocyanine.
The above pigment dispersant may comprise the present invention acrylic acid-maleic acid copolymer (or its salt), but may further comprise other components such as polymeric phosphoric acid and any salt thereof, phosphonic acid and any salt thereof, and polyvinyl alcohol, or may further comprise polymers (or their salts) other than the present invention acrylic acid-maleic acid copolymer (or its salt) if they do not hinder the performance or effects of the pigment dispersant.
If a small amount of the pigment dispersant comprising the present invention acrylic acid-maleic acid copolymer (or its salt) is added to a pigment instead of conventional pigment dispersants and dispersed into water along with the pigment, then high concentration pigment slurries such as high concentration calcium carbonate slurries can be produced wherein the high concentration pigment slurries have a low viscosity and a high fluidity, and further, a good stability of these properties over a period of time.
The amount of the pigment dispersant, as used, comprising the present invention acrylic acid-maleic acid copolymer (or its salt), is preferably in the range of 0.05xcx9c2 wt %, more preferably 0.1xcx9c1.0 wt %, still more preferably 0.2xcx9c0.8 wt %, in terms of the ratio of the present invention acrylic acid-maleic acid copolymer (or its salt) to the pigment. In the case where the amount of the pigment dispersant, as used, is smaller than 0.05 wt %, the dispersibility tends to be insufficient. In the case where the amount exceeds 2 wt %, effects rewarding the increase in the amount of addition tends to be unexpectable.
(Fiber-treating agent):
Even in regions where the magnesium ion content in water is high, the fiber-treating agent comprising the present invention acrylic acid-maleic acid copolymer (or its salt) exhibits high dispersibility and high effects of improving the detergency, and further, can prevent the magnesium hydroxide scale from being deposited to fibers and thus deteriorating their hygroscopicity and touch. Therefore, this fiber-treating agent can favorably be used in the steps, such as scouring, dyeing, bleaching, and soaping steps, in the treatment of fibers.
The acrylic acid-maleic acid copolymer (or its salt) may be used alone as the fiber-treating agent, but also can be used in the form of a composition further comprising additives such as dyeing agents, peroxides, and surfactants. As to the above additive, those which are usually used for conventional fiber-treating agents are available. The ratio between the acrylic acid-maleic acid copolymer (or its salt) and the above additive is such that the above additive is added in the ratio of preferably 0.1xcx9c100 weight parts, more preferably 0.2xcx9c80 weight parts, still more preferably 1xcx9c50 weight parts, per 1 weight part of the acrylic acid-maleic acid copolymer (or its salt), for example, in order to improve the degree of whiteness, color evenness and degree of dyed colorfastness of fibers. In the case where the amount of the above additive is smaller than 0.1 weight part, the effect due to the addition tends to be insufficient. In the case where the amount exceeds 100 weight parts, the acrylic acid-maleic acid copolymer (or its salt) tends to be unable to exhibit their effects. The fiber-treating agent, comprising the present invention acrylic acid-maleic acid copolymer (or its salt), may further comprise acrylic acid-maleic acid copolymers (or their salts) other than the present invention acrylic acid-maleic acid copolymer (or its salt) if they do not hinder the performance or effects of the fiber-treating agent. The content of the present invention acrylic acid-maleic acid copolymer (or its salt) in the fiber-treating agent is not especially limited, but is preferably in the range of 1xcx9c100 wt %, more preferably 5xcx9c100 wt %, of the entirety of the fiber-treating agent.
The fiber for which the fiber-treating agent comprising the present invention acrylic acid-maleic acid copolymer (or its salt) can be used is not especially limited. However, examples thereof include cellulose fibers, such as cotton and hemp; chemical fibers, such as nylon and polyester; animal fibers, such as wool and silk; semisynthetic fibers, such as rayon; and any fabric and blend thereof.
In the case where the fiber-treating agent comprising the present invention acrylic acid-maleic acid copolymer (or its salt) is applied to the scouring step, it is preferable that the present invention acrylic acid-maleic acid copolymer (or its salt) is mixed with alkali agents and surfactants. For the bleaching step, it is preferable that the present invention acrylic acid-maleic acid copolymer (or its salt) is mixed with peroxides and with silicic chemicals, which are used as inhibitors of alkaline bleachers from decomposition, such as sodium silicate.
In this part II, detailed descriptions are given on the present invention production process for the aqueous maleic salt solution and on the present invention maleic acid copolymer (or its salt) resultant from this aqueous solution.
First of all, the production process for the aqueous maleic salt solution, according to the present invention, comprises the steps of: charging 80% or less of the required amount of a basic substance to produce the aqueous maleic salt solution and 80% or less of the required amount of maleic acid (or its salt) and/or maleic anhydride to produce the aqueous maleic salt solution into a reaction vessel; and then adding thereto the respective balances of water, the basic substance, and the maleic acid (or its salt) and/or maleic anhydride under conditions where the highest value of the reaction temperature will be 80xc2x0 C. or higher; thus obtaining the aqueous maleic salt solution with a formed malic acid content of not more than 10,000 ppm, therefore, with high purity.
Examples of the basic substance, as initially charged, include: alkaline metal hydroxides, such as sodium hydroxide and potassium hydroxide; alkaline earth metal hydroxides, such as calcium hydroxide and magnesium hydroxide; and ammonia water. These may be used either alone respectively or in combinations with each other. Preferable ones are alkaline metal salts, and the most preferable one is sodium hydroxide.
As to the basic substance, 80% or less, preferably 60% or less, most preferably 50% or less, of the required amount thereof to produce the aqueous maleic salt solution is initially charged into the reaction vessel. In the case where more than 80% of the required amount is initially charged, a large amount of malic acid is unfavorably formed.
In addition, the maleic acid (or its salt) and/or maleic anhydride, as initially charged, may be in any form of melted products of maleic anhydride, solids (e.g. powders or tablets) of maleic anhydride, melted products of maleic acid (so-called hydrous maleic acid), solids (e.g. powders or tablets) of maleic acid (the same as above), and aqueous solutions of maleic acid (either of anhydrous and hydrous ones). These may be used either alone respectively or in combinations with each other. Particularly, the melted products of maleic anhydride are preferable.
As to the maleic acid, 80% or less, preferably 60% or less, most preferably 50% or less, of the required amount thereof to produce the aqueous maleic salt solution is initially charged into the reaction vessel. In the case where more than 80% of the required amount is initially charged, there are disadvantages in that the amount of fumaric acid being formed greatly increases. The fumaric acid is an isomer of maleic acid and consumed in the polymerization, but fumaric acid has the disadvantage of having much lower polymerizability than maleic acid, therefore making it very difficult to control the molecular weight and the molecular weight distribution, and increasing the amount of residual monomers.
Next, after initially charging the above materials under the above conditions, the respective balances of water, the basic substance, and the maleic acid (or its salt) and/or maleic anhydride are added, when the highest value of the reaction temperature needs to be 80xc2x0 C. or higher, and is preferably 100xc2x0 C. or higher, and is most preferably so high as to produce a boiling point reflux state. In the case where the reaction temperature is below 80xc2x0 C., the neutralization will unfavorably need a very long time.
In addition, the molar ratio of the maleic acid (or its salt) and/or maleic anhydride to the basic substance in the reaction system is preferably maintained in the range of 1:4xcx9c4:1 for 90% or more of a period of time when the reaction temperature is 100xc2x0 C. or higher. This ratio is more preferably maintained in the range of 1:3xcx9c3:1, and most preferably in the range of 1:2xcx9c2:1. Especially, when the reaction temperature is 110xc2x0 C. or higher, the above ratio is preferably maintained in the range of 1:3xcx9c3:1, and more preferably in the range of 1:2xcx9c2:1. In the case where the molar ratio of the basic substance is more than the above ranges, there are disadvantages in that the amount of malic acid being formed greatly increases. In the case where the molar ratio of the maleic acid (or its salt) and/or maleic anhydride is more than the above ranges, the amount of fumaric acid being formed greatly increases, so there are disadvantages for the aforementioned reason.
Furthermore, the aqueous maleic salt solution, as produced by the initial charging and the dropping, has a solid component concentration of preferably 40 wt % or higher, more preferably 45 wt % or higher, most preferably 50 wt % or higher, at the end of the reaction. In the case where the solid component concentration of the aqueous maleic salt solution is lower than 40 wt %, there are disadvantages, for example, in that the polymerization using such an aqueous maleic salt solution implies a low solid component concentration in the polymerization and therefore greatly lowers the productivity or greatly deteriorates the polymerizability of maleic acid. In addition, as the solid component concentration becomes higher, the productivity preferably becomes better. However, in the case where the solid component concentration exceeds 75 wt %, there are disadvantages in that the water solubility and the stability of the resultant aqueous maleic salt solution are deteriorated.
In the above way, the aqueous maleic salt solution with a formed malic acid content of not more than 10,000 ppm, therefore, with high purity can be obtained. Incidentally, the reason why malic acid is chosen as the impurity is because malic acid is a product by addition reaction of water to maleic acid, and is presumed to be easily formed as a by-product, namely, an impurity, during the neutralization, and is actually formed in the largest quantity among the impurities. The malic acid content in this aqueous maleic salt solution of high purity is preferably not more than 7,000 ppm, more preferably not more than 5,000 ppm, still more preferably not more than 4,000 ppm, most preferably not more than 2,000 ppm.
Next, explanations are made on the maleic acid copolymer (or its salt) as obtained from this aqueous maleic salt solution of high purity. However, the use of the present invention aqueous maleic salt solution is not limited thereto.
The maleic acid copolymer (or its salt), according to the present invention, is a maleic acid/acrylic acid copolymer (or its salt), which comprises maleic acid (or its salt) of 30xcx9c70 mol % and acrylic acid (or its salt) of 70xcx9c30 mol %, and has a weight-average molecular weight of 2,000xcx9c50,000, a calcium ion scavengeability of 400 mg CaCO3/g or more, a clay dispersibility of 0.6 or more, and a malic acid content of not more than 9 wt % in the solid content of the copolymer (or its salt).
The calcium ion scavengeability is defined as the mg number, in terms of calcium carbonate, of calcium ion as scavenged by 1 g of copolymer (or its salt), and is an index to show how much calcium ion in water the maleic acid scavenges. The surfactant becomes insoluble upon bonding to calcium ion in water. However, if the maleic acid copolymer (or its salt) having high calcium ion scavengeability is used together with the surfactant, then the surfactant is prevented from becoming insoluble, so that a great effect upon improving the detergency is produced. The calcium ion scavengeability of the present invention copolymer (or its salt) is 400 mg CaCO3/g or more, and preferably 420 mg CaCO3/g or more. The increase in the calcium ion scavengeability has the advantage of enhancing the ability of the maleic acid copolymer (or its salt) as the detergent builder. However, an attempt to obtain a copolymer (or its salt) having a calcium ion scavengeability more than 490 mg CaCO3/g might lower the production efficiency or involve high cost.
The clay dispersibility is an index for evaluation of effects upon removing and uniformly dispersing the dirt such as mud dirt, thereby preventing the clay from precipitating, in the course of washing. To sufficiently obtain such effects, the clay dispersibility of the present invention copolymer (or its salt) is 0.6 or more, and preferably 0.8 or more. The increase in the clay dispersibility has the advantage of enhancing the ability of the maleic acid copolymer (or its salt) as the detergent builder. However, an attempt to obtain a copolymer (or its salt) having a clay dispersibility more than 1.5 might lower the production efficiency or involve high cost.
The malic acid content in the solid content of the copolymer (or its salt) is an index to show how large amount of low-molecular impurity is contained in the maleic acid copolymer (or its salt). Incidentally, the reason why malic acid is chosen as the impurity is not only such as aforementioned about the neutralization step, but also that maleic acid is polymerized in the aqueous solution, and further that, especially in the case where hydrogen peroxide is used as the polymerization initiator, malic acid is presumed to be easily formed, and is actually formed in the largest quantity among the impurities. The ratio of the malic acid content to the solid content of the present invention copolymer (or its salt) is not more than 9 wt %, and preferably not more than 7 wt %, more preferably not more than 5 wt %. The decrease in the malic acid content has the advantage of enhancing the ability of the maleic acid copolymer (or its salt) as the detergent builder. However, in the case where hydrogen peroxide is used as the polymerization initiator under the below-mentioned conditions, an attempt to obtain a copolymer (or its salt) having a malic acid content of not more than 3 wt % might lower the production efficiency or involve high cost.
In addition, the monomer components of the present invention maleic acid copolymer (or its salt) comprises maleic acid (or its salt) of 30xcx9c70 mol % and acrylic acid (or its salt) of 70xcx9c30 mol %, and, if necessary, can further comprise another water-soluble monoethylenic monomer of 5 mol % or less.
As to the maleic acid (or its salt), the aforementioned aqueous maleic salt solution is preferably used, and, according to cases, maleic acid and/or maleic anhydride may further be used fitly. In the case where the ratio of the maleic acid (or its salt) is less than 30 mol %, there are disadvantages in that the copolymer (or its salt) having high calcium ion scavengeability is extremely difficult to obtain. In addition, in the case where the ratio of the maleic acid (or its salt) exceeds 70 mol %, there are disadvantages in that the polymerizability tends to greatly be deteriorated, and further that the resultant copolymer (or its salt) tends to have a greatly deteriorated clay dispersibility.
As to the acrylic acid (or its salt), either of acrylic acid and acrylic salt may be used, and any mixture thereof is also available. The acrylic salt is obtainable by neutralization with the aforementioned basic substance. In the case where the ratio of the acrylic acid (or its salt) is less than 30 mol %, there are disadvantages in that the polymerizability tends to greatly be deteriorated, and further that the resultant copolymer (or its salt) tends to have a greatly deteriorated clay dispersibility. In addition, in the case where the ratio of the acrylic acid (or its salt) exceeds 70 mol %, there are disadvantages in that the copolymer (or its salt) having high calcium ion scavengeability is extremely difficult to obtain.
Examples of the above other water-soluble monoethylenic monomer, as used in the amount of 5 mol % or less if necessary, include unsaturated monocarboxylic acid monomers, such as methacrylic acid, xcex1-hydroxyacrylic acid and crotonic acid, and any salt thereof; unsaturated polycarboxylic acid monomers, such as fumaric acid, itaconic acid, citraconic acid and aconitic acid, and any salt thereof; vinyl acetate; hydroxyl-group-containing unsaturated monomers, such as 3-methyl-3-buten-1-ol (isoprenol), 3-methyl-2-buten-1-ol (prenol), 2-methyl-3-buten-2-ol (isoprene alcohol), and monomers as formed from addition reactions of 1xcx9c100 mol of ethylene oxide and/or propylene oxide to 1 mol of the above monomers; (meth)allyl etheric unsaturated monomers, such as glycerol monoallyl ether and monomers as formed from addition reactions of 1xcx9c100 mol of ethylene oxide and/or propylene oxide to 1 mol of glycerol monoallyl ether; sulfonic-acid-group-containing unsaturated monomers, such as 3-allyloxy-2-hydroxypropanesulfonic acid, vinylsulfonic acid, allylsulfonic acid, methallylsulfonic acid, styrenesulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, sulfoethyl (meth)acrylate, sulfopropyl (meth)acrylate, 2-hydroxysulfopropyl (meth)acrylate and sulfoethylmaleimide, and any salt thereof; terminal-alkyl-group-containing esteric unsaturated monomers, such as (i) monoesters, as formed from reactions of alcohols with unsaturated monocarboxylic acid monomers (e.g. (meth)acrylic acid and crotonic acid), or (ii) monoesters, any salt thereof, or diesters, as formed from reactions of alcohols with unsaturated polycarboxylic acid monomers (e.g. maleic acid, fumaric acid, itaconic acid, citraconic acid, and aconitic acid), wherein the alcohols are products from addition reactions of 0xcx9c100 mol of ethylene oxide and/or propylene oxide to alkyl alcohols having 1xcx9c20 carbon atoms; esteric unsaturated monomers, such as (iii) monoesteric monomers, as formed from addition reactions of 1xcx9c100 mol of ethylene oxide and/or propylene oxide to 1 mol of unsaturated carboxylic acid monomers (e.g. (meth)acrylic acid and crotonic acid), or (iv) monoesters, any salt thereof, or diesteric monomers, as formed from addition reactions of 1xcx9c100 mol of ethylene oxide and/or propylene oxide to 1 mol of unsaturated polycarboxylic acid monomers (e.g. maleic acid, fumaric acid, itaconic acid, citraconic acid, and aconitic acid).
Furthermore, the weight-average molecular weight of the present invention copolymer (or its salt) is in the range of 2,000xcx9c50,000, preferably, 5,000xcx9c15,000. In the case where the weight-average molecular weight is less than 2,000, there are disadvantages in that the calcium ion scavengeability is greatly deteriorated. In the case where the weight-average molecular weight exceeds 50,000, there are disadvantages in that the clay dispersibility is greatly deteriorated.
Next, explanations are made on the present invention production process for the maleic acid copolymer (or its salt). The present invention copolymer (or its salt) is obtainable by any production process, but, particularly preferably, produced by the below-mentioned process.
As to the maleic acid (or its salt), preferably 50 wt % or more, more preferably 70 wt % or more, most preferably the entirety, of the amount thereof as used is charged into the reaction vessel prior to the reaction. In the case where the charging amount prior to the reaction is smaller than 50 wt %, there are disadvantages in that a large amount of maleic acid (or its salt) might remain after the end of the polymerization. In addition, the concentration of the maleic acid (or its salt) at the initiation of the polymerization is usually 40 wt % or more, preferably 45 wt % or more, more preferably 50 wt % or more. In the case where the charging concentration is smaller than 40 wt %, there are disadvantages in that a large amount of maleic acid (or its salt) might remain after the end of the polymerization.
As to the acrylic acid (or its salt), preferably 50 wt % or more, more preferably 70 wt % or more, most preferably the entirety, of the amount thereof as used is dropwise supplied into the reaction vessel after the initiation of the polymerization. In the case where the amount exceeding 50 wt % is charged prior to the reaction, there are disadvantages in that, because acrylic acid (or its salt) has much higher polymerizability than maleic acid, it is remarkably difficult to control the molecular weight and the molecular weight distribution. The dropping period of time is in the range of usually 30xcx9c300 minutes, preferably 60xcx9c180 minutes, after the initiation of the reaction. Such a dropping period of time has the advantage of narrowing the molecular weight distribution of the resultant maleic acid copolymer (or its salt) and therefore enhancing the calcium ion scavengeability and the clay dispersibility. Also for enhancing the productivity, it is preferable to finish dropping the acrylic acid (or its salt) in a short period of time. However, dropping shorter than 30 minutes has the disadvantage of involving a large amount of residual maleic acid after the end of the polymerization, or having a possibility that much reaction heat might be generated in a short period of time to make it difficult to remove the heat. In addition, dropping longer than 300 minutes is unfavorable, because it greatly deteriorates the productivity and is therefore economically disadvantageous.
In addition, as to the aforementioned other water-soluble monoethylenic monomer, the initially charging amount and the dropping amount thereof may be determined optionally according to the polymerizability thereof. The dropping period of time is also optional, but it is preferable that the dropping end is earlier than that of acrylic acid (or its salt).
As to the polymerization solvent, aqueous solvents are used. Preferably 80 wt % or more, most preferably 100 wt %, thereof is water. Examples of hydrophilic organic solvents, usable jointly with water as the aqueous solvent, include: lower alcohols, such as methanol, ethanol, and isopropyl alcohol; amides, such as diethylformamide; and ethers, such as diethyl ether. These may be used either alone respectively or in combinations with each other.
In the present invention, hydrogen peroxide is preferably used as a water-soluble polymerization initiator. The amount of hydrogen peroxide, as used, is preferably within the range of 2xcx9c8 g, more preferably 3xcx9c5 g, per mol of the monomer components. In the case where the amount of hydrogen peroxide, as used, is smaller than 2 g, there are disadvantages in that a large amount of maleic acid remains, and that the molecular weight of the resulting copolymer (or its salt) is too high, thus resulting in low clay dispersibility. In addition, in the case where more than 9 g of hydrogen peroxide is used, there are disadvantages in that the amount of residual hydrogen peroxide is too large at the end of the polymerization.
Considering the simplification of production facilities, the cost saving, and effects of lessening the amount of hydrogen peroxide remaining at the end of the polymerization, it is preferable to finish dropping hydrogen peroxide earlier than the dropping end of acrylic acid (or its salt) by 20 minutes or more. The above production conditions can reduce the concentration of hydrogen peroxide, remaining after the end of the polymerization, to 2 wt % or lower, more preferably 1 wt % or lower, still more preferably 0.5 wt % or lower, of the entirety of the reaction liquid. In addition, the production conditions can reduce the amount of maleic acid, remaining after the end of the polymerization, to 3 wt % or smaller, more preferably 1 wt % or smaller, of the entirety of the reaction liquid. In the case where the amount of residual maleic acid is larger than 3 wt %, unfavorably, there might be problems in that crystals of maleic acid are deposited in places where it is cold in winter.
In the present invention production process, other water-soluble polymerization initiators may further be used, if necessary. Examples thereof include: persulfuric acid salts, such as ammonium persulfate, sodium persulfate and potassium persulfate; azo compounds, such as 2,2xe2x80x2-azobis(2-a midinopropane) dihydrochloride, 4,4xe2x80x2-azobis-(4-cyanovaleric acid), 2,2xe2x80x2-azobisisobutyronitrile and 2,2xe2x80x2-azobis(4-methoxy-2,4-dimethylvaleronitrile); organic peroxides, such as benzoyl peroxide, lauroyl peroxide, peracetic acid, persuccinic acid, di-tertiary-butyl peroxide, di-tertiary-butyl hydroperoxide and cumene hydroperoxide. It is also permissible to use any mixture of at least two members selected from the group consisting of these compounds. Particularly preferred ones are the persulfuric acid salts such as ammonium persulfate, sodium persulfate and potassium persulfate. Incidentally, the entirety of the water-soluble polymerization initiator is, preferably, dropwise supplied into the reaction vessel. The beginning and ending times of the dropping are optional, but, preferably, the dropping end of the water-soluble polymerization initiator is 10xcx9c20 minutes later than that of acrylic acid (or its salt). If so, the amount of residual acrylic acid can be reduced very much.
In addition, if necessary, polyvalent metals are usable to raise the efficiency of the above initiator. Examples of usable effective polyvalent metal ions include: iron ions, vanadium-atom-containing ions, and copper ions. Among the polyvalent metal ions, preferable ones are Fe3+, Fe2+, Cu+, Cu2+, V2+, V3+ and VO2+, and more preferable ones are Fe3+, Cu2+ and VO2+. These polyvalent metal ions may be used either alone respectively or in combinations with each other. The concentration of the polyvalent metal ions is preferably in the range of 0.1 to 100 ppm of the entirety of the reaction liquid. In the case where the concentration is lower than 0.1 ppm, few effects are seen. In the case where the concentration is higher than 100 ppm, the resulting maleic acid copolymer (or its salt) is highly colored, and it might therefore be impossible to use such a copolymer (or its salt) as a component of detergent compositions.
The form in which the polyvalent metal ions are supplied is not especially limited, and any metal compound and any metal can be used if it becomes ionized in the polymerization reaction system. Examples of such metal compounds and metals include: water-soluble metal salts, such as vanadium oxytrichloride, vanadium trichloride, vanadium oxalate, vanadium sulfate, vanadic anhydride, ammonium metavanadate, ammonium hypo-vanadious [(NH4)2SO4.VSO4.6H2O], ammonium vanadious [(NH4)V(SO4)2.12H2O], copper(II) acetate, copper(II) bromide, copper(II) acetylacetate, cupric chloride, ammonium cuprous chloride, copper carbonate, copper(II) chloride, copper(II) citrate, copper(II) formate, copper(II) hydroxide, copper nitrate, copper naphthenate, copper(II) oleate, copper maleate, copper phosphate, copper(II) sulfate, cuprous chloride, copper(I) cyanide, copper iodide, copper(I) oxide, copper thiocyanate, iron acetylacetonate, ammonium iron citrate, ammonium ferric oxalate, ammonium ferrous sulfate, ammonium ferric sulfate, iron citrate, iron fumarate, iron maleate, ferrous lactate, ferric nitrate, iron pentacarbonyl, ferric phosphate and ferric pyrophosphate; metal oxides, such as vanadium pentaoxide, copper(II) oxide, ferrous oxide and ferric oxide; metal sulfides, such as copper(II) sulfide and iron sulfide; and copper powder and iron powder.
The above metal compounds and metals may be charged into the reaction vessel at any time before the end of the reaction, but is preferably charged thereto before the initiation of the reaction.
The pH value during the polymerization reaction can be selected optionally. However, preferably for enhancing the polymerizability of maleic acid, the pH is in the range of 5xcx9c13 at the initiation of the polymerization, and is then decreased with the progress of the polymerization. Examples of basic compounds for neutralization, as used to adjust the pH during the polymerization, include: hydroxides and carbonates of alkaline metals such as sodium, potassium and lithium; ammonia; alkylamines such as monomethylamine, diethylamine, trimethylamine, monoethylamine, dimethylamine and triethylamine; alkanolamines such as monoethanolamine, diethanolamine, triethanolamine, isopropanolamine and secondary-butanolamine; and pyridine. It is also permissible to use any mixture of at least two members selected from the group consisting of these compounds.
In the present invention, the monomer component, the polymerization initiator, the aqueous solvent, and other raw materials (usable if necessary), as mentioned above, need to be used in amounts such that the theoretical solid component concentration will be 40 wt % or more after the end of the polymerization. In the case where the theoretical solid component concentration is less than 40 wt %, bad influences are unfavorably produced upon the calcium ion scavengeability and the clay dispersibility, because the resultant molecular weight is low, and because the resultant molecular weight distribution is broad.
As to other polymerization conditions, the polymerization temperature is preferably 80xc2x0 C. or higher, and more preferably near the boiling point of the polymerization solvent. In the case where the polymerization temperature is lower than 80xc2x0 C., there are disadvantages in that the amount of residual maleic acid is greatly increased. In addition, the polymerization pressure is not especially limited, but any of normal pressure (atmospheric pressure), an increased pressure, and a reduced pressure is available.
By the above production process, the present invention maleic acid copolymer (or its salt) is obtainable.
Next, explanations are made on uses of the present invention maleic acid copolymer (or its salt). The present invention copolymer (or its salt) is, for example, used for detergent compositions, inorganic-pigment dispersants, water-treating agents, and fiber-treating agents.
The above detergent composition comprises the present invention copolymer (or its salt) and a surfactant. In the detergent composition, the concentration of the copolymer (or its salt) is preferably within the range of 0.1 to 20 wt %, more preferably within the range of 0.5 to 15 wt %, and the concentration of the surfactant is preferably within the range of 5 to 70 wt %, more preferably within the range of 20 to 60 wt %.
As to the surfactant, any of anionic surfactants, nonionic surfactants, amphoteric surfactants and cationic surfactants is usable.
Examples of the anionic surfactant include alkylbenzenesulfonic acid salts, alkyl or alkenyl ether sulfuric acid salts, alkyl or alkenyl sulfuric acid salts, xcex1-olefinsulfonic acid salts, xcex1-sulfofatty acids or any ester salt thereof, alkanesulfonic acid salts, saturated or unsaturated fatty acid salts, alkyl or alkenyl ether carboxylic acid salts, amino acid surfactants, N-acylamino acid surfactants, and alkyl or alkenyl phosphoric acid esters or any salt thereof.
Examples of the nonionic surfactant include polyoxyalkylene alkyl ethers, polyoxyalkylene alkenyl ethers, polyoxyethylene alkyl phenyl ethers, higher fatty acid alkanolamide or any alkylene oxide addition product thereof, sucrose fatty acid esters, alkyl glycoxides, fatty acid glycerol monoesters, and alkylamine oxides.
Examples of the amphoteric surfactant include carboxy or sulfobetaine amphoteric surfactants.
Examples of the cationic surfactant include quaternary ammonium salts.
The detergent composition containing the present invention copolymer (or its salt) may further comprise an enzyme, if necessary. Examples of the enzyme, as can be mixed, include protease, lipase, and cellulase. Particularly preferred are protease, alkaline lipase, and alkaline cellulase, all of which are highly active in alkaline washing liquids. The amount of the enzyme, as mixed, is preferably within the range of 0.01 to 5 wt % of the entirety of the detergent composition. In the case where the amount deviates from this range, the balance with the surfactant is lost, so the enhancement of the detergency is impossible. If necessary, the detergent composition containing the present invention copolymer (or its salt) may further comprise components which are usually used for conventional detergent compositions, such as alkaline builders, chelate builders, re-attachment inhibitors, fluorescent agents, bleachers and perfumes. In addition, zeolite may also be added. Examples of usable alkaline builders include silicic acid salts, carbonic acid salts, and sulfuric acid salts. Examples of the chelate builder, as can be used if necessary, include diglycolic acid, oxycarboxylic acid salts, EDTA (ethylenediaminetetraacetic acid), DTPA (diethylenetriaminehexaacetic acid), and citric acid.
The above inorganic-pigment dispersant may comprise the present invention copolymer (or its salt) only, or may further comprise other components such as polymeric phosphoric acid and any salt thereof, phosphonic acid and any salt thereof, and polyvinyl alcohol. In either case, the inorganic-pigment dispersant exhibits good performance as a dispersant for inorganic pigments, such as heavy or light calcium carbonate (as used for paper coating) and clay. If a small amount of the inorganic-pigment dispersant comprising the present invention copolymer (or its salt) is added to an inorganic pigment and dispersed into water along with the pigment, then high concentration inorganic pigment slurries such as high concentration calcium carbonate slurries can be produced wherein the high concentration inorganic pigment slurries have a low viscosity and a high fluidity, and further, a good stability of these properties over a period of time. The amount of the inorganic-pigment dispersant, as used, is preferably within the range of 0.05 to 2.0 weight parts per 100 weight parts of the inorganic pigment.
The copolymer (or its salt) of the present invention may be used alone as the water-treating agent, or may be used as the water-treating agent in the form of a composition which further comprises additives such as polymeric phosphoric acid salts, phosphonic acid salts, anticorrosive agents, slime controlling agents, and chelating agents. Either case is useful for inhibiting the formation of scale in systems such as cooling water circulation systems, boiler water circulation systems, seawater desalination plants, pulp digesters, and black liquor evaporators.
The above fiber-treating agent comprises the present invention copolymer (or its salt) and at least one member selected from the group consisting of dyeing agents, peroxides and surfactants, and can be used in the steps, such as scouring, dyeing, bleaching, and soaping steps, in the treatment of fibers. As to the above dyeing agents, peroxides, and surfactants, those which are usually used for conventional fiber-treating agents are available. The ratio between the copolymer (or its salt) and the at least one member selected from the group consisting of dyeing agents, peroxides and surfactants is such that the at least one member selected from the group consisting of dyeing agents, peroxides and surfactants is added in the ratio of 0.1xcx9c100 weight parts per 1 weight part of the copolymer (or its salt), for example, in order to improve the degree of whiteness, color evenness and degree of dyed colorfastness of fibers. The fiber for which the fiber-treating agent can be used is not especially limited. However, examples thereof include cellulose fibers, such as cotton and hemp; chemical fibers, such as nylon and polyester; animal fibers, such as wool and silk; semisynthetic fibers, such as rayon; and any fabric and blend thereof. In the case where the fiber-treating agent is applied to the scouring step, it is preferable that the present invention copolymer (or its salt) is mixed with alkali agents and surfactants. For the bleaching step, it is preferable that the present invention copolymer (or its salt) is mixed with peroxides and with silicic chemicals, which are used as inhibitors of alkaline bleachers from decomposition, such as sodium silicate.
(Effects and Advantages of the Invention):
The acrylic acid-maleic acid copolymer (or its salt) of the present invention does not only maintain conventional performance levels of the metal ion scavengeability, the clay dispersibility, and the scale inhibitability upon calcium ion, but is also at high level in performances with regard to magnesium ion as have never been studied, such as magnesium ion scavengeability, clay dispersibility in the presence of magnesium ion, and scale inhibitability upon magnesium ion. Thus, the acrylic acid-maleic acid copolymer (or its salt) of the present invention is a copolymer (or its salt) which is excellent with good balance in performances, such as metal ion scavengeability, clay dispersibility, calcium carbonate scale inhibitability, and magnesium hydroxide scale inhibitability, even in regions where the magnesium ion content in water is high.
The production process of the present invention can give the above excellent acrylic acid-maleic acid copolymer (or its salt) with ease and good efficiency, therefore, at a low cost, and further, with a small amount of residual monomer at the end of the polymerization, therefore, with high productivity. The reason why the resultant acrylic acid-maleic acid copolymer (or its salt) displays the above excellent performances is considered to be that maleic acid and acrylic acid are introduced into the resultant copolymer (or its salt) at high random. Especially, it is considered that the good performances are displayed because the resultant copolymer (or its salt) merely has a very low proportion of moieties where maleic acid is polymerized in the block form.
Because the present invention detergent composition comprises the above present invention acrylic acid-maleic acid copolymer (or its salt) and because this copolymer (or its salt) has high magnesium ion scavengeability as above, the present invention detergent composition prevents the surfactant from bonding to magnesium ion in water and thus becoming insoluble even in regions where the magnesium ion content in water is high. Therefore, the present invention detergent composition has a great effect upon improving the detergency to oil dirt. In addition, because the present invention acrylic acid-maleic acid copolymer (or its salt), as contained in the present invention detergent composition, is excellent also in the clay dispersibility in the presence of magnesium ion, the present invention detergent composition exhibits high detergency to mud dirt even in regions where the magnesium ion content in water is high. Furthermore, because the present invention acrylic acid-maleic acid copolymer (or its salt), as contained in the present invention detergent composition, is excellent also in the magnesium hydroxide scale inhibitability, the present invention detergent composition can prevent the magnesium hydroxide scale from being deposited to clothes and thus deteriorating their hygroscopicity and touch even in regions where the magnesium ion content in water is high.
Because of comprising the above present invention acrylic acid-maleic acid copolymer (or its salt), the present invention detergent builder is excellent in the dispersibility and the chelating ability, and contributes to the enhancement of the detergency of detergents, even in regions where the magnesium ion content in water is high.
The present invention further can provide a production process for an aqueous maleic salt solution which contains only a small amount of formed impurities such as malic acid and therefore has high purity. In addition, the present invention can provide a maleic acid copolymer (or its salt) which is obtained from the resultant aqueous solution and therefore also contains only a small amount of impurities such as malic acid and therefore exhibits high calcium ion scavengeability and high clay dispersibility. Accordingly, if this copolymer (or its salt) is, for example, used for detergent compositions, inorganic-pigment dispersants, water-treating agents, and fiber-treating agents, then very excellent performance is displayed.
In this part 1, the present invention is more specifically illustrated by the following examples of some preferred embodiments of the present invention acrylic acid-maleic acid copolymer (or its salt) and its production process and use in comparison with comparative examples not according to the invention. However, the invention is not limited to these examples.